Injectible two-stage compression rotary compressor

ABSTRACT

An injectable two-stage compression rotary compressor includes a compressor housing; a low-stage compressing section provided in the compressor house; a high-stage compressing section provided near the low-stage compressing section; a motor for driving the low-stage compressing section and the high-stage compressing section; an accumulator held at an outer side portion of the compressor housing; a low-pressure connecting pipe connecting the accumulator and the low-stage compressing section; an intermediate connecting pipe connecting the low-stage compressing section and the high-stage compressing section outside the compressor housing; and an intermediate suction pipe for introducing a medium pressure injection refrigerant into the intermediate connecting pipe. The intermediate suction pipe is connected to the intermediate connecting pipe so that an outlet of the intermediate suction pipe faces in a flowing direction of a medium pressure gas refrigerant in the intermediate connecting pipe.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an injectable two-stage compressionrotary compressor used for a heat pump system utilizing an injectionrefrigerating cycle and specifically to a compressor where a mediumpressure injection refrigerant, which is a high dryness wet refrigerantof a refrigerating cycle side, is introduced into an intermediateconnecting pipe of a medium pressure gas refrigerant atmosphere.

2. Description of the Related Art

A conventional two-stage compression rotary compressor includes alow-stage compressing section and a high-stage compressing sectiondisposed in a sealed cylindrical compressor housing, a motor for drivingthe low-stage compressing section and the high-stage compressingsection, and an accumulator disposed beside the compressor housing.

The compressor housing is provided with a first communication hole, asecond communication hole, and a third communication hole in a line in adirection of a rotary shaft. In the second communication hole, alow-stage suction pipe connected to a suction side of the low-stagecompressing section to draw in a low pressure refrigerant is dispose.

In the first communication hole, a low-stage discharge pipe connected toa discharge side of the low-stage compressing section to discharge alow-stage discharge refrigerant outside the compressor housing isdisposed. In the third communication hole, a high-stage suction pipeconnected to a suction side of the high-stage compressing section todraw in the low-stage discharge refrigerant is disposed.

The low-stage suction pipe and a lower portion of the accumulator areconnected by a low-pressure connecting pipe. The low-stage dischargepipe and the high-stage suction pipe are connected by an intermediateconnecting pipe. Into the intermediate connecting pipe, an injectionrefrigerant separated by a gas-liquid separator of a refrigerating cycleis injected via an intermediate suction pipe. An outlet of theintermediate suction pipe faces perpendicularly to a flow of a mediumpressure gas refrigerant in the intermediate connecting pipe.

For example, Japanese Patent Application Laid-open No. 2006-152931discloses a rotary compressor as described above.

Normally, pressure in the intermediate connecting pipe of the two-stagecompression rotary compressor becomes medium due to the dischargedrefrigerant from the low-stage compressing section and then graduallyreduces due to suction by the high-stage compressing section andpressure pulsation occurs in a cycle according to a rotational speed ofthe compressor.

When a discharge stroke of the low-stage compressing section ends, thelow-stage compressing section and the intermediate connecting pipe aredisconnected from each other. Because the high-stage compressing sectionis 180° out of phase, it is in a suction stroke at this time. Becausethe sum of a volume of the intermediate connecting pipe and a volume ofthe high-stage compressing section is the smallest at this time,pressure in the intermediate connecting pipe is the highest at thistime. When phase further advances, the suction stroke of the high-stagecompressing section proceeds and the volume increases and therefore thepressure in the intermediate connecting pipe reduces as a rollerrotates. As a result, the pressure pulsation increases in theintermediate connecting pipe.

If the outlet of the intermediate suction pipe is connected to beperpendicular to the intermediate connecting pipe, the flow of themedium pressure gas refrigerant in the intermediate connecting pipe anda flow of the injection refrigerant discharged from the intermediatesuction pipe become orthogonal to each other. Therefore, the pressurepulsation in the intermediate connecting pipe further increases, thepressure pulsation propagates into injection piping, and a pressure lossof the injection refrigerant increases. As a result, compressionefficiency of the compressor is impaired.

SUMMARY OF THE INVENTION

It is an object of the present invention to at least partially solve theproblems in the conventional technology.

According to an aspect of the present invention, an injectable two-stagecompression rotary compressor used for a heat pump system utilizing aninjection refrigerating cycle, includes a sealed cylindrical compressorhousing in which first, second, and third communication holes aresequentially provided apart in an axial direction on an outer peripheralwall thereof; a low-stage compressing section provided within thecompressor housing with one end of a low-stage suction pipe connected toa low-stage suction hole through the second communication hole and oneend of a low-stage discharge pipe connected to a low-stage mufflerdischarge hole through the first communication hole; a high-stagecompressing section provided near the low-stage compressing sectionwithin the compressor housing with one end of a high-stage suction pipeconnected to a high-stage suction hole through the third communicationhole and a high-stage muffler discharge hole communicating with aninside of the compressor housing; a motor for driving the low-stagecompressing section and the high-stage compressing section; a sealedcylindrical accumulator held at an outer side portion of the compressorhousing; a low-pressure connecting pipe connecting a bottomcommunication hole of the accumulator and the other end of the low-stagesuction pipe; an intermediate connecting pipe connecting the other endof the low-stage discharge pipe and the other end of the high-stagesuction pipe; and an intermediate suction pipe for introducing a mediumpressure injection refrigerant into the intermediate connecting pipe,the medium pressure injection refrigerant being a wet refrigerant of theinjection refrigerating cycle side. The intermediate suction pipe isconnected to the intermediate connecting pipe so that an outlet of theintermediate suction pipe faces in a flowing direction of a mediumpressure gas refrigerant in the intermediate connecting pipe.

The above and other objects, features, advantages and technical andindustrial significance of this invention will be better understood byreading the following detailed description of presently preferredembodiments of the invention, when considered in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a basic structure of a refrigerating cycle of an airconditioner;

FIG. 1B is a vertical sectional view showing a first embodiment of aninjectable two-stage compression rotary compressor of the airconditioner according to the present invention;

FIG. 1C is a cross sectional view of a low-stage compressing section anda high-stage compressing section of the two-stage compression rotarycompressor;

FIG. 1D is a cross sectional view taken along line A-A of FIG. 1B;

FIG. 1E is a cross sectional view of a low-stage end plate;

FIG. 1F is a sectional view taken along line B-B of FIG. 1E;

FIG. 1G is a front view of a compressor housing;

FIG. 1H is a side view of the injectable two-stage compression rotarycompressor in the first embodiment;

FIG. 1I is a vertical sectional view showing a variation of theinjectable two-stage compression rotary compressor in the firstembodiment;

FIG. 1J is a vertical sectional view showing another variation of theinjectable two-stage compression rotary compressor in the firstembodiment;

FIG. 2 is a side view of a second embodiment of the injectable two-stagecompression rotary compressor of the air conditioner according to theinvention; and

FIG. 3 is a side view of a third embodiment of the injectable two-stagecompression rotary compressor of the air conditioner according to theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of an injectable two-stage compression rotary compressoraccording to the present invention will be described below in detailwith reference to the drawings. The invention is not limited to theembodiments.

First Embodiment

FIG. 1A shows a basic structure of a refrigerating cycle of an airconditioner, FIG. 1B is a vertical sectional view showing a firstembodiment of an injectable two-stage compression rotary compressor ofthe air conditioner according to the invention, FIG. 1C is a crosssectional view of a low-stage compressing section and a high-stagecompressing section of the two-stage compression rotary compressor, FIG.1D is a cross sectional view taken along line A-A of FIG. 1B, FIG. 1E isa cross sectional view of a low-stage end plate, FIG. 1F is a sectionalview taken along line B-B of FIG. 1E, FIG. 1G is a front view of acompressor housing, FIG. 1H is a side view of the injectable two-stagecompression rotary compressor in the first embodiment, FIG. 1I is avertical sectional view showing a variation of the injectable two-stagecompression rotary compressor in the first embodiment, and FIG. 1J is avertical sectional view showing another variation of the injectabletwo-stage compression rotary compressor in the first embodiment.

As shown in FIG. 1A, the refrigerating cycle (heat pump system) of theair conditioner in the first embodiment includes the injectabletwo-stage compression rotary compressor (hereafter simply referred to asthe “compressor”) 1, a condenser (radiator) 4, a first expansionmechanism section 7A, a second expansion mechanism section 7B, anevaporator (heat absorber) 9, and basic cycle piping 2 for connectingthem in an annular shape.

The compressor 1 is the injectable two-stage compression rotarycompressor including a low-stage compressing section 12L and ahigh-stage compressing section 12H. An intermediate suction pipe 108(see FIG. 1B) for drawing in an injection refrigerant at medium pressurebetween condenser pressure and evaporator pressure is connected to anintermediate connecting pipe 23 for connecting the low-stage compressingsection 12L and the high-stage compressing section 12H. The compressor 1is a so-called inverter compressor having a motor with a rotationalspeed variable according to a power supply frequency.

The first expansion mechanism section 7A is a variable throttlemechanism for optimizing pressure of the condenser (radiator) 4 andpressure of the evaporator (heat absorber) 9 with outside airtemperature and indoor set temperature. The second expansion mechanismsection 7B is a variable throttle mechanism for optimizing an amount ofthe injection refrigerant. The basic cycle piping 2 connects the abovedevices in order and circulates the refrigerant.

The heat pump system of the air conditioner includes a branch pipe 5,injection piping 6, and an internal heat exchanger 8 as well. The branchpipe 5 is disposed in the basic cycle piping 2 and between the condenser(radiator) 4 and the first expansion mechanism section 7A to cause therefrigerant to branch into a basic cycle and an injection cycle.

The injection piping 6 connects the branch pipe 5 and the intermediatesuction pipe 108 with the second expansion mechanism section 7Binterposed therebetween. The internal heat exchanger 8 exchange heatbetween a basic cycle piping 2 a disposed between the branch pipe 5 andthe first expansion mechanism section 7A and an injection piping 6 adisposed between the second expansion mechanism section 7B and theintermediate suction pipe 108.

In the heat pump system of the air conditioner, a four-way valve 3 forreversing a flowing direction of the refrigerant in the basic cycle isconnected to the compressor 1 in order to provide for cooling andheating. If the four-way valve 3 is reversed, functions of the condenser(radiator) 4 and the evaporator (heat absorber) 9 are reversed. In FIG.1A, the four-way valve 3 is in such a state that a heat exchangerconnected between the four-way valve 3 and the branch pipe 5 functionsas the condenser and therefore heating operation is carried out if theheat exchanger is disposed in an indoor unit.

The heat pump system of the air conditioner in the first embodiment isan example that is injectable only in the heating operation when theheat exchanger connected between the four-way valve 3 and the branchpipe 5 is disposed in the indoor unit. By adding changeover piping forreversely connecting the condenser (radiator) 4 and the evaporator (heatabsorber) 9 to the first expansion mechanism section 7A on the basiccycle and to the internal heat exchanger 8 and the branch pipe 5, thesystem become injectable during cooling as well. Although flows of thebasic cycle refrigerant and the injection refrigerant in the internalheat exchanger 8 are parallel flows in the heat pump system of the airconditioner in the first embodiment, it is also possible to installpiping so that they become counterflows.

Next, with reference to FIG. 1A, the flow of the refrigerant during theheating operation in the heat pump system of the air conditioner in thefirst embodiment will be described. The high-temperature andhigh-pressure gas refrigerant discharged from the compressor 1 exchangesheat with air in the condenser (radiator) 4, dissipates heat, andbecomes liquid. Here, part of the liquefied refrigerant branches at thebranch pipe 5 and becomes the injection refrigerant flowing through theinjection piping 6 and the rest of the refrigerant becomes the basiccycle refrigerant flowing through the basic cycle piping 2.

Pressure of the injection refrigerant flowing into the injection piping6 is reduced in the second expansion mechanism section 7B to mediumpressure Pm and the refrigerant is brought into a two-phase state atmedium temperature and exchanges heat with the refrigerant flowingthrough the basic cycle piping 2 a in the internal heat exchanger 8 whenit flows through the injection piping 6 a in the internal heat exchanger8 to thereby absorb heat to obtain higher dryness. Then, the injectionrefrigerant meets discharged gas from the low-stage compressing section12L and is drawn into the high-stage compressing section 12H in agenerally gasified state.

On the other hand, the refrigerant flowing through the basic cyclepiping 2 exchanges heat with the medium temperature injectionrefrigerant flowing through the injection piping 6 a in the internalheat exchanger 8 when it flows through the basic cycle piping 2 a in theinternal heat exchanger 8 to thereby dissipate heat and be supercooledto a greater degree. Then, pressure of the refrigerant flowing throughthe basic cycle piping 2 is reduced in the first expansion mechanismsection 7A and the refrigerant comes into a low temperature and lowpressure two-phase state and exchanges heat with air in the evaporator(heat absorber) 9 to thereby absorb heat to come into a superheatedstate.

Then, the superheated refrigerant flows through the four-way valve 3 anda low-pressure connecting pipe 31 of the compressor 1 and is drawn intothe low-stage compressing section 12L. The refrigerant drawn into thelow-stage compressing section 12L is compressed in the low-stagecompressing section 12L. After the refrigerant is discharged from thelow-stage compressing section 12L, it meets the injection refrigerantand is drawn into the high-stage compressing section 12H.

The refrigerant drawn into the high-stage compressing section 12H iscompressed in the high-stage compressing section 12H to high pressurethat is final discharge pressure and discharged into a compressorhousing 10 of the compressor 1. The refrigerant discharged into thecompressor housing 10 of the compressor 1 is discharged outside thecompressor housing 10 through a discharge pipe 107.

Next, the injectable two-stage compression rotary compressor 1 of theair conditioner of the first embodiment will be described. As shown inFIG. 1B, the compressor 1 of the first embodiment includes a compressingsection 12 and a motor 11 for driving the compressing section 12 in thesealed cylindrical compressor housing 10.

A stator 111 of the motor 11 is fixed by shrink fitting to an innerperipheral face of the compressor housing 10. A rotor 112 of the motor11 is disposed at a center of the stator 111 and is fixed by shrinkfitting to a shaft 15 that mechanically connects the motor 11 and thecompressing section 12.

The compressing section 12 includes the low-stage compressing section12L and the high-stage compressing section 12H connected in series tothe low-stage compressing section 12L and disposed above the low-stagecompressing section 12L. As shown in FIGS. 1B and 1C, the low-stagecompressing section 12L has a low-stage cylinder 121L and the high-stagecompressing section 12H has a high-stage cylinder 121H.

In the low-stage cylinder 121L and the high-stage cylinder 121H,low-stage and high-stage cylinder bores 123L and 123H are formed,respectively, to be concentric with the motor 11. In the respectivecylinder bores 123L and 123H, cylindrical low-stage and high-stagepistons 125L and 125H having smaller outside diameters than the borediameters are disposed, respectively, to form compression spaces forcompressing the refrigerant between the cylinder bore 123L and thelow-stage piston 125L and between the cylinder bore 123H and thehigh-stage piston 125H, respectively.

In each of the cylinders 121L and 121H, a groove as high as the cylinderis formed to extend radially from the cylinder bore 123L or 123H. In thegroove, a plate-shaped low-stage or high-stage vane 127L or 127H isfitted. Each of the vanes 127L and 127H is mounted, on its side facingthe compressor housing 10, with a low-stage or high-stage spring 129L or129H.

With repulsive forces of the springs 129L and 129H, tip ends of thevanes 127L and 127H are pushed against outer peripheral faces of thepistons 125L and 125H and the vanes 127L and 127H partition thecompression spaces into low-stage and high-stage suction chambers 131L,131H and low-stage and high-stage compression chambers 133L and 133H.

The cylinders 121L and 121H are provided with low-stage and high-stagesuction holes 135L and 135H communicating with the suction chambers 131Land 131H to draw the refrigerant into the suction chambers 131L and131H.

Between the low-stage cylinder 121L and the high-stage cylinder 121H, anintermediate partitioning plate 140 is disposed to partition thecompression spaces into the space in the low-stage cylinder 121L and thespace in the high-stage cylinder 121H. Below the low-stage cylinder121L, a low-stage end plate 160L is disposed to close a lower side ofthe compression space in the low-stage cylinder 121L. Above thehigh-stage cylinder 121H, a high-stage end plate 160H is disposed toclose an upper side of the compression space in the high-stage cylinder121H.

On the low-stage end plate 160L, a lower bearing portion 161L is formed.A lower portion 151 of the shaft 15 is rotatably supported on the lowerbearing portion 161L. On the high-stage end plate 160H, an upper bearingportion 161H is formed. A middle portion 153 of the shaft 15 is fittedin the upper bearing portion 161H.

The shaft 15 has eccentric low-stage crank portion 152L and high-stagecrank portion 152H with a 180° phase shift from each other. Thelow-stage crank portion 152L retains the low-stage piston 125L of thelow-stage compressing section 12L for rotation and the high-stage crankportion 152H retains the high-stage piston 125H of the high-stagecompressing section 12H for rotation.

If the shaft 15 rotates, the low-stage and high-stage pistons 125L and125H rotate while rolling on inner peripheral walls of the low-stage andhigh-stage cylinder bores 123L and 123H. Following the pistons 125L and125H, the low-stage and high-stage vanes 127L and 127H reciprocate. Dueto the motions of the low-stage and high-stage pistons 125L and 125H andthe low-stage and high-stage vanes 127L and 127H, capacities of thelow-stage and high-stage suction chambers 131L and 131H and thelow-stage and high-stage compression chambers 133L and 133H continuouslychange and the compressing section 12 continuously draws in, compresses,and discharges the refrigerant.

Below the low-stage end plate 160L, a low-stage muffler cover 170L isdisposed to form a low-stage muffler chamber 180L between the low-stageend plate 160L and the low-stage muffler cover 170L. A discharge portionof the low-stage compressing section 12L opens into the low-stagemuffler chamber 180L. In other words, in the low-stage end plate 160L, alow-stage discharge hole 190L connecting the compression space in thelow-stage cylinder 121L and the low-stage muffler chamber 180L isformed. In the low-stage discharge hole 190L, a low-stage dischargevalve 200L for preventing backflow of the compressed refrigerant isdisposed.

As shown in FIGS. 1D and 1E, the low-stage muffler chamber 180L is asingle annular chamber and is part of an intermediate connecting passageconnecting a discharge side of the low-stage compressing section 12L anda suction side of the high-stage compressing section 12H.

As shown in FIGS. 1E and 1F, on the low-stage discharge valve 200L, alow-stage discharge valve guard 201L for restricting a flexible valveopening amount of the low-stage discharge valve 200L is fixed togetherwith the low-stage discharge valve 200L by a rivet 203. In an outerperipheral wall portion of the low-stage end plate 160L, a low-stagemuffler discharge hole 210L for discharging the refrigerant in thelow-stage muffler chamber 180L is formed. The low-stage mufflerdischarge hole 210L and the high-stage suction hole 135H are formed inthe same direction on a circumference.

Above the high-stage end plate 160H, a high-stage muffler cover 170H isdisposed to form a high-stage muffler chamber 180H between thehigh-stage end plate 160H and the high-stage muffler cover 170H. In thehigh-stage end plate 160H, a high-stage discharge hole 190H connectingthe compression space in the high-stage cylinder 121H and the high-stagemuffler chamber 180H is formed. In the high-stage discharge hole 190H, ahigh-stage discharge valve 200H for preventing backflow of thecompressed refrigerant is disposed. On the high-stage discharge valve200H, a high-stage discharge valve guard 201H for restricting a flexiblevalve opening amount of the high-stage discharge valve 200H is fixedtogether with the high-stage discharge valve 200H by a rivet.

The low-stage cylinder 121L, the low-stage end plate 160L, the low-stagemuffler cover 170L, the high-stage cylinder 121H, the high-stage endplate 160H, the high-stage muffler cover 170H, and the intermediatepartitioning plate 140 are fastened together by bolts (not shown). Anouter peripheral portion of the high-stage end plate 160H of thecompressing section 12 fastened together by the bolts is secured to thecompressor housing 10 by spot welding. In this way, the compressingsection 12 is fixed to the compressor housing 10.

As shown in FIG. 1G, in an outer peripheral wall of the cylindricalcompressor housing 10, a first communication hole 101, a secondcommunication hole 102, and a third communication hole 103 are formed inthis order upward from a lower portion while spaced from each other inan axial direction. The first communication hole 101, the secondcommunication hole 102, and the third communication hole 103 are formedin the same circumferential positions of the compressor housing 10.

As shown in FIGS. 1B and 1H, an accumulator 25 formed of a separatecylindrical sealed container is retained by an accumulator holder 251and an accumulator band 253 in a circumferential position with arightward phase shift from the front (the circumferential position wherethe first communication hole 101, the second communication hole 102, andthe third communication hole 103 are formed) of an outer side portion ofthe compressor housing 10 in order to avoid interference with piping(described later).

To a center of a top portion of the accumulator 25, a system connectingpipe 255 connected to the refrigerating cycle side is connected. To abottom communication hole 257 formed at a center of a bottom portion ofthe accumulator 25, the low-pressure connecting pipe 31 is connected.The low-pressure connecting pipe 31 has one end extending to an upperportion inside the accumulator 25 and the other end connected to theother end of a low-stage suction pipe 104.

To the low-stage muffler discharge hole 210L of the low-stage mufflerchamber 180L, one end of a low-stage discharge pipe 105 is connectedthrough the first communication hole 101. To the high-stage suction hole135H of the high-stage cylinder 121H, one end of a high-stage suctionpipe 106 is connected through the third communication hole 103. Theother end of the low-stage discharge pipe 105 and the other end of thehigh-stage suction pipe 106 are connected by the intermediate connectingpipe 23 bent into a U shape in a two-dimensional manner. Thelow-pressure connecting pipe 31 is bent at right angles at two positionsin a three-dimensional manner in order to avoid interference with theU-shaped intermediate communication pipe 23.

The intermediate communication passage connecting the discharge side ofthe low-stage compressing section 12L and the suction side of thehigh-stage compressing section 12H is formed of the low-stage mufflerchamber 180L, the low-stage muffler discharge hole 210L, theintermediate connecting pipe 23, and the suction hole 135H of thehigh-stage compressing section 12H. To a U-shape upper portion (adownstream side) of the intermediate connecting pipe 23, theintermediate suction pipe 108 (described later) is connected.

A temperature sensor 240 for measuring temperature of the refrigerantdischarged from the low-stage muffler chamber 180L is attached to anouter face of a portion of the intermediate connecting pipe 23 which ison an upstream side of a junction with the intermediate suction pipe 108and is near the low-stage compressing section 12L.

The discharge portion of the high-stage compressing section 12Hcommunicates with an inside of the compressor housing 10 via thehigh-stage muffler chamber 180H. In other words, the high-stage endplate 160H is provided with the high-stage discharge hole 190Hconnecting the compression space in the high-stage cylinder 121H and thehigh-stage muffler chamber 180H. In the high-stage discharge hole 190H,the high-stage discharge valve 200H for preventing backflow of thecompressed refrigerant is disposed. The discharge portion of thehigh-stage muffler chamber 180H communicates with the inside of thecompressor housing 10. To the top portion of the compressor housing 10,the discharge pipe 107 for discharging the high pressure refrigerant tothe refrigerating side is connected.

Lubricating oil is encapsulated in the compressor housing 10 to a levelof the high-stage cylinder 121H and is circulated through thecompressing section 12 by a vane pump (not shown) inserted into a lowerportion of the shaft 15 to lubricate sliding members and seal portionswhere minute gaps partition the compression space for the compressedrefrigerant.

As shown in FIGS. 1B and 1H, as a structure characterizing thecompressor 1 in the first embodiment, a tip end portion of theintermediate suction pipe 108 formed into the L shape is inserted intoand connected (welded) to the upper portion of the intermediateconnecting pipe 23 having a greater diameter than the intermediatesuction pipe 108. An outlet at the tip end portion of the intermediatesuction pipe 108 faces in substantially the same direction as a flowingdirection of the medium pressure gas refrigerant in the intermediateconnecting pipe 23. In this way, depending on conditions, it is possibleto jet out the injection refrigerant having a higher flow rate than themedium pressure gas refrigerant to exert an ejector effect.

In other words, the injection refrigerant jetted out from theintermediate suction pipe 108 draws in the medium pressure gasrefrigerant from the low-stage compressing section 12L and makes it easyto draw it into the high-stage compressing section 12H. As a result, apressure loss of the medium pressure gas refrigerant can be reduced,suction pressure of the high-stage compressing section 12H can beincreased, and efficiency of the compressor 1 can be enhanced.

FIG. 1I shows a variation of the compressor 1 in the first embodiment.In this variation, the outlet of the tip end portion of the intermediatesuction pipe 108 inserted into the upper portion of the intermediateconnecting pipe 23 is cut diagonally to be parallel to an inner wall ofthe intermediate connecting pipe 23. Because the tip end portion of theintermediate suction pipe 108 inserted into the intermediate connectingpipe 23 is cut, flow path resistance of the medium pressure gasrefrigerant reduces, the pressure loss can be further reduced, andefficiency of the compressor 1 can be further enhanced.

FIG. 1J shows another variation of the compressor 1 in the firstembodiment. In this variation, the outlet of the tip end portion of theintermediate suction pipe 108 formed into an L shape is inserted upwardinto a lower portion of the intermediate connecting pipe 23 and theintermediate suction pipe 108 and the intermediate connecting pipe 23are connected (welded) to each other. The outlet of the tip end portionof the intermediate suction pipe 108, facing in substantially the samedirection as the flowing direction of the medium pressure gasrefrigerant in the intermediate connecting pipe 23, provides the ejectoreffect. In this way, it is possible to obtain similar effects to thoseof the above examples.

Second Embodiment

FIG. 2 is a side view of a second embodiment of the injectable two-stagecompression rotary compressor of the air conditioner according to theinvention. As a structure characterizing a compressor 1B in the secondembodiment, the low-stage muffler discharge hole 210L (see FIG. 1E) isprovided in a radial direction in a position with a leftward phase shiftin a circumferential direction of the compressor housing 10 from thelow-stage suction hole 135L (see FIG. 1C) and the high-stage suctionhole 135H of the compressing section 12.

As shown in FIG. 2, the cylindrical compressor housing 10 is provided,in its outer peripheral wall, with the first communication hole 101, thesecond communication hole 102, and the third communication hole 103 inthis order upward from a lower portion while spaced from each other inan axial direction. The second communication hole 102 and the thirdcommunication hole 103 are provided in the same circumferential position(front) of the compressor housing 10 and the first communication hole101 is provided in a different circumferential position (a positiondisplaced leftward) from the second communication hole 102 and the thirdcommunication hole 103.

The low-pressure connecting pipe 31 for introducing the low pressurerefrigerant in the refrigerating cycle into the low-stage compressingsection 12L via the accumulator 25 is connected to the low-stage suctionhole 135L of the low-stage cylinder 121L with the second communicationhole 102 and the low-stage suction pipe 104 interposed therebetween. Thelow-pressure connecting pipe 31 is bent into a shape of a quarter of acircle in a two-dimensional manner between the low-stage suction pipe104 and the bottom communication hole 257 of the accumulator 25.

To the low-stage muffler discharge hole 210L of the low-stage mufflerchamber 180L, one end of the low-stage discharge pipe 105 is connectedthrough the first communication hole 101. To the high-stage suction hole135H of the high-stage cylinder 121H, one end of the high-stage suctionpipe 106 is connected through the third communication hole 103. Theother end of the low-stage discharge pipe 105 and the other end of thehigh-stage suction pipe 106 are connected by the intermediate connectingpipe 23 bent into a U shape in a two-dimensional manner.

The first communication hole 101 is provided in the differentcircumferential position (the position displaced leftward) from thesecond and third communication holes 102 and 103 so that thelow-pressure connecting pipe 31 and the intermediate connecting pipe 23do not interfere with each other. The method of connecting theintermediate suction pipe 108 and the intermediate connecting pipe 23 isthe same as that in the first embodiment (including the variation andthe other variation).

In the compressor 1B in the second embodiment, the low-pressureconnecting pipe 31 can be bent at one position into the arc shape in thetwo-dimensional manner, which facilitates working of low-pressureconnecting pipe 31 and reduces cost. Moreover, duct resistance of thelow-pressure connecting pipe 31 can be reduced, a suction pressure losscan be reduced, and compression efficiency of the compressor 1B can beenhanced.

Third Embodiment

FIG. 3 is a side view showing a third embodiment of the injectabletwo-stage compression rotary compressor of the air conditioner accordingto the invention. As a structure characterizing a compressor 1C in thethird embodiment, the low-stage suction hole 135L (see FIG. 1C) of thecompressing section 12 is provided in a radial direction in a positionwith a rightward phase shift in a circumferential direction of thecompressor housing 10 from the low-stage muffler discharge hole 210L(see FIG. 1E) and the high-stage suction hole 135H.

As shown in FIG. 3, the cylindrical compressor housing 10 is provided,in its outer peripheral wall, with the first communication hole 101, thesecond communication hole 102, and the third communication hole 103 inthis order upward from a lower portion while spaced from each other inan axial direction. The first communication hole 101 and the thirdcommunication hole 103 are provided in substantially the samecircumferential position (front) of the compressor housing 10 and thesecond communication hole 102 is provided in a different circumferentialposition (a position displaced rightward) from the first communicationhole 101 and the third communication hole 103 so that the low-pressureconnecting pipe 31 and the intermediate connecting pipe 23 do notinterfere with each other.

As shown in FIG. 3, the accumulator 25 formed of a separate cylindricalsealed container is retained by the accumulator holder 251 and theaccumulator band 253 in a position with a rightward phase shift from thefront (substantially the same circumferential position as the secondcommunication hole 102) of an outer side portion of the compressorhousing 10. To a center of a top portion of the accumulator 25, thesystem communication hole 255 connected to the refrigerating cycle sideis connected. To the bottom communication hole 257 formed at a center ofa bottom portion of the accumulator 25, the low-pressure connecting pipe31 is connected. The low-pressure connecting pipe 31 has one endextending to an upper portion inside the accumulator 25 and the otherend connected to the other end of the low-stage suction pipe 104.

The low-pressure connecting pipe 31 for introducing the low pressurerefrigerant in the refrigerating cycle into the low-stage compressingsection 12L via the accumulator 25 is connected to the low-stage suctionhole 135L of the low-stage cylinder 121L with the second communicationhole 102 and the low-stage suction pipe 104 interposed therebetween. Thelow-pressure Connecting pipe 31 is bent into a shape of a quarter of acircle in a two-dimensional manner between the low-stage suction pipe104 and the bottom communication hole 257 of the accumulator 25.

To the low-stage muffler discharge hole 210L of the low-stage mufflerchamber 180L, one end of the low-stage discharge pipe 105 is connectedthrough the first communication hole 101. To the high-stage suction hole135H of the high-stage cylinder 121H, one end of the high-stage suctionpipe 106 is connected through the third communication hole 103. Theother end of the low-stage discharge pipe 105 and the other end of thehigh-stage suction pipe 106 are connected by the intermediate connectingpipe 23 bent into a U shape in a two-dimensional manner. The secondcommunication hole 102 is provided in the different circumferentialposition (the position displaced rightward) from the first and thirdcommunication holes 101 and 103 so that the low-pressure connecting pipe31 and the intermediate connecting pipe 23 do not interfere with eachother.

As described above, in the rotary compressor 1C of the third embodiment,the first communication hole 101 and the third communication hole 103 inthe compressor housing 10 are disposed in substantially the samecircumferential position (front) of the compressor housing 10 and thesecond communication hole 102 is disposed in the differentcircumferential position (the position displaced rightward) from thefirst and third communication holes 101 and 103 so that the low-pressureconnecting pipe 31 and the intermediate connecting pipe 23 do notinterfere with each other.

As a result, similarly to the second embodiment, the low-pressureconnecting pipe 31 can be bent at one position into the U shape in thetwo-dimensional manner, which can be facilitated working of thelow-pressure connecting pipe 31 and reduced cost. Moreover, ductresistance of the low-pressure connecting pipe 31 can be reduced, asuction pressure loss can be reduced, and compression efficiency of thecompressor 1C can be enhanced.

Because the pressure loss in the low-pressure connecting pipe 31increases during high rotation operation of the motor 11 with thevariable rotational speed, i.e., when a circulating refrigerant flowrate is large, it is possible to enhance the efficiency of thecompressors 1B and 1C by bending the low-pressure connecting pipe 31 atone position to reduce the pressure loss as in the second and thirdembodiments.

In the embodiment of the injectable two-stage compression rotarycompressor according to the present invention, the flow of the mediumpressure gas refrigerant in the intermediate connecting pipe and a flowof the injection refrigerant jetted out from the outlet of theintermediate suction pipe are parallel to each other, which reducespressure pulsation in the intermediate connecting pipe, reduces asuction loss in the high-stage compressing section, and enhancesefficiency of the compressor.

Although the invention has been described with respect to a specificembodiment for a complete and clear disclosure, the appended claims arenot to be thus limited but are to be construed as embodying allmodifications and alternative constructions that may occur to oneskilled in the art that fairly fall within the basic teaching herein setforth.

1. An injectable two-stage compression rotary compressor used for a heatpump system utilizing an injection refrigerating cycle, the compressorcomprising: a sealed cylindrical compressor housing in which first,second, and third communication holes are sequentially provided apart inan axial direction on an outer peripheral wall thereof; a low-stagecompressing section provided within the compressor housing with one endof a low-stage suction pipe connected to a low-stage suction holethrough the second communication hole and one end of a low-stagedischarge pipe connected to a low-stage muffler discharge hole throughthe first communication hole; a high-stage compressing section providednear the low-stage compressing section within the compressor housingwith one end of a high-stage suction pipe connected to a high-stagesuction hole through the third communication hole and a high-stagemuffler discharge hole communicating with an inside of the compressorhousing; a motor for driving the low-stage compressing section and thehigh-stage compressing section; a sealed cylindrical accumulator held atan outer side portion of the compressor housing; a low-pressureconnecting pipe connecting a bottom communication hole of theaccumulator and the other end of the low-stage suction pipe; anintermediate connecting pipe connecting the other end of the low-stagedischarge pipe and the other end of the high-stage suction pipe; and anintermediate suction pipe for introducing a medium pressure injectionrefrigerant into the intermediate connecting pipe, the medium pressureinjection refrigerant being a wet refrigerant of the injectionrefrigerating cycle side, wherein the intermediate suction pipe isconnected to the intermediate connecting pipe so that an outlet of theintermediate suction pipe faces in a flowing direction of a mediumpressure gas refrigerant in the intermediate connecting pipe.
 2. Theinjectable two-stage compression rotary compressor according to claim 1,wherein the second and third communication holes are provided insubstantially the same circumferential position of the compressorhousing, the first communication hole is provided in a differentcircumferential position from the second and third communication holes,the accumulator is held in substantially the same circumferentialposition as the second and third communication holes, and thelow-pressure connecting pipe and the intermediate connecting pipe, eachbeing bent in a two-dimensional manner, are provided so thatinterference between the low-pressure connecting pipe and theintermediate connecting pipe is avoided.
 3. The injectable two-stagecompression rotary compressor according to claim 1, wherein the firstand third communication holes are provided in substantially the samecircumferential position of the compressor housing, the secondcommunication hole is provided in a different circumferential positionfrom the first and third communication holes, the accumulator is held insubstantially the same circumferential position as the secondcommunication hole, and the low-pressure connecting pipe and theintermediate connecting pipe, each being bent in a two-dimensionalmanner, are provided so that interference between the low-pressureconnecting pipe and the intermediate connecting pipe is avoided.
 4. Aninjectable two-stage compression rotary compressor according to claim 1,adapted to variable rotational speed drive.